Process of surface-coating iron



rams FUN-l JS ll. COEI'RADSON, OF

TO ALBERT \V. HALE,

PRQCESS 0F nnoonnrn, new roan,

or PLAINFIELD, new JnnsnY.

SURFACE COATiN ASSIGNOR OF ONE-HALF G IRON.

EIEESIPECATIOH forming part of Letters Patent NOhGlLZQQ, dated January 27, 1.885.

Application filed August l3, 1883. Renewed July 1. 1834. (Specimens) "UH/0TH, 'ntrty cancer/1 known that I, Porrrns H. CONRADSON, en of pWQLlQ/ll, and a resident ot Brookthe county of Kings and State of New tve invented certain new and useful nents in Processes of Surface-Coating hthe following is a specification. n relates to the coating of iron el surfaces for protecting them against .md eorrosion'such as caused by the acand water when such coating is by chemical act-ion on the metal itdistinct from coatings which are apelectroplating or by pigments, &c, invention consists in producing upon surface oi ii? 21 and steel articles and marats a thin coating of metallic sulphide or by chemical action of sulphurous vapors upon the metal heated in the e of air and such oxygen-containing which, by easily decomposing, ethe metal to be attached by free oxygen,

to oxidize it. niy preierred modeof procedure to effect coating is as follows: inlet-iron, cast-iron, or steel, orniaterials reef -such asplates, bars,

8:c.-are inclosed .ir-tight chamber or muffle-oven, from east of carbonic acid,

with its oxygen except at higher temitures than necessary to produce C-lllS coat- The air being thus expelled, the mate are heated to about 500 to 600 centi- At the same time sulphur is vaporso-G centigrade) and the vapor introduced into the tor a few petal While the latter is atof 590 to (300, thereby forming, at action on the metal oi iron. it a thicker coating is ne essary a little longer upon the metal. is then left to cool in the inuii'le.

surface of the iron thus the eye the mum." to said sulphide,

desired,

c and not liable to rust and corrode.

might those produced by tempering The articles of the air is expelled by introducing a (which gas does not by heating it inaseparate retort, (at about generated is inuitle and allowed to act minutes upon the surface of the kept at the aforesaid by cheniitself, a coating oi sulto allow the sulphur-'va- The The treated pre-' ornamental yellowish and leaves a cut coating which is not infected by air it is not even necessary that rust previously formed upon the surface of the same should be first removed, as even the dust of the rust is converted into sulphide.

In treating the iron as aforesaid care should be taken not-to increase the temperature to a red heat, as this would produce,with the sulphur-vapors, a protosulphide, which will not withstand the action of air and water, and will not prevent oxidation or rust.

Instead of sulphur-vapor formed by boiling the sulphur, as before stated, sulphurcted hydrogen may be introduced; but the coating formed thereby (sesqui-sulphide, pyrrhotinc, or magnetic pyrites) has a tendency to peel off, which is not the case with the bisulphide or common hard-iron pyrites formed by the aforesaid treatment.

Varieties of shades o In treating the iron color analogous to steel may be obtained upon the sulphuretcd surface by admit ting for a few moments (more or less, according to the color desired) a small quantity of air into the rnuflie after the iron has partly cooled.

To produce a greater variety of tints 1 coat the iron with another metah-such as copper previous to submitting it to the action of the sulphurous vapor, thereby producing a coating of the mixed sulphides of the iron and copper. The peculiar brownish luster ol' the sulphide of copper produces, with the yellowish luster ot the sulphide of iron,

feet.

The mode in which tocoat the iron with copper is immaterial; but it may preferably be i done by simply a brief immersion of the iron into a solution of a copper salt. l I am aware that it has been proposed long ago to color polished surfaces of copper by l sulphureted hydrogen or other sulphurous vapors or liquids for the purpose of producing ornamentation, and I lay no claim to such coloring. 4 1 Having thus described my invention, 1 claim 1. The mode of protecting articles and materials of iron and steel from corrosiomwhich consists in forming a coating ol' sulphuret on their surfaces by chemical tlCljlUll.

the desired et- Q new and desire to soon ro by Letters l atcnt 2. The mode of protecting articles and mam y invention I have signed my name, in pres I terials of iron and steel from corrosiomwhich ence of two witnesses, this 2d (lay of August,

consists in forming a coating of sulphide on 1883.

their surfaces by subjecting them in a heated PONTUS I-I. OONRADSON. 5 state and in the absence of air to the action of XVitncsses:

vapor of sulphur. R0131. W. MATTHEWs,

In testimony that I claim the foregoing as A. WV. ALMQVIST. 

